In brief:
Partial answer

Stimulants definitely increase dopamine, which is concentrated in a very old part of the brain called the mid-brain and, among other things, is involved in reward systems.

There are strong connections between this part of the brain and the frontal cortex, which is where some problems associated with adhd seem to arise. Exactly why this works so well is still unknown.

In brief:
Partial answer

Stimulants definitely increase dopamine, which is concentrated in a very old part of the brain called the mid-brain and, among other things, is involved in reward systems.

There are strong connections between this part of the brain and the frontal cortex, which is where some problems associated with adhd seem to arise. Exactly why this works so well is still unknown.
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